Climate control system

ABSTRACT

A climate control system includes a closed vessel containing a phase change material for absorbing heat from or emitting heat to an environment in which the system is intended to be arranged. The closed vessel also contains a solid heat conducting medium for facilitating heat transfer within the vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/GB2014/051147, filed Apr. 11, 2014, which claims the benefit of GBApplication No. GB 1306625.3, filed Apr. 11, 2013. Each of theabove-referenced patent applications is incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a climate control system, and inparticular, to a climate control system that incorporates a phase changematerial.

2. Description of the Related Technology

Climate control systems for maintaining the temperature of internalspaces, including living spaces and work spaces, at a comfortable levelare well-known.

In typical cooling air conditioning systems, a refrigerant undergoes anactively driven vapor compression cycle consisting of four main phases:

compression;

condensation;

expansion; and

evaporation.

The energy used in operating the vapor compression cycle in such systemsis considerable. Aside from the financial cost associated with providingthe energy to run active climate control systems of this type, there aresignificant environmental considerations surrounding their use. In 2000,5% of non-domestic UK building energy was consumed by cooling andventilation equipment and this figure has been rising since. However,for health reasons, it is important that the climate inside buildings ismaintained at a comfortable level so it is clear that a need for climatecontrol systems remains in spite of their drawbacks.

In order to reduce the energy costs of operating climate controlsystems, it has been proposed to use passive rather than active climatecontrol systems. One such example is the ILKATHERM ceiling productmanufactured by ILKAZELL Isoliertechnik GmbH and described in theEuropean patent application published as EP 2039844. This productcomprises a pre-fabricated ceiling tile with a layer of gypsumimpregnated with a phase change material. Phase change materials have ahigh latent heat capacity, which enables them to absorb or emit aconsiderable amount of heat as they change state. The phase changematerials that are most suitable for passively maintaining human comfortlevels change from the solid to the liquid phase within a temperaturerange of around 20-30° C. An example of such a phase change material isMicronal®, which is used in the ILKAZELL product and comprises smallamounts of paraffin wax encapsulated in microscopic acrylic glass balls.

As the temperature in a room containing an ILKAZELL ceiling tile rises,the wax within the acrylic glass balls in the ceiling tile starts tochange state from a solid to a liquid, absorbing heat from the room inthe process. In reverse, as the room cools, the wax changes back from aliquid to a solid, emitting heat into the room in the process.

As an alternative to the ILKAZELL ceiling tile product, a similarproduct, also manufactured by ILKAZELL, and in the form of a sail thathangs within a space to be cooled is also available. ILKAZELL wallboards of a similar composition are also available.

In addition to the energy savings that can be achieved from usingpassive climate control systems, such as the ILKAZELL products, a keybenefit of such systems is that they do not require servicing.

However, a significant disadvantage of the ILKAZELL products is theirlimited passive thermal and cooling capacity, which is due partly to arestriction on the amount of Micronal® material that can be incorporatedinto the products by virtue of the limit on the overall individualproduct volume, but also to the limitation on the number of productsthat can usefully be provided in a given internal space, the physicaldimensions of the target space being an obvious limiting factor.

It is an object of the present invention to provide a more effectivepassive climate control system than prior art passive climate controlsystems.

SUMMARY

In accordance with one aspect of the present invention, there isprovided a climate control system comprising a closed vessel comprisinga phase change material for absorbing heat from or emitting heat to anenvironment in which the system is intended to be arranged; and a solidheat conducting medium for facilitating heat transfer within the vesseland the solid heat conducting medium is in the form of a random packing.

One benefit of using a phase change material in climate control systemsis that phase change materials are effective in removing heat from oremitting heat to their surrounding environment in a passive manner,which both conserves energy and enables the provision of a simpleclimate control system that does not require regular servicing. Inaddition, containing the phase change material in a closed vessel offersflexibility in the amount of phase change material that can be employedin a climate control system, in contrast in particular to prior artproducts in which phase change material is impregnated in small amountsthrough an existing item. However, phase change materials are notinherently good conductors of heat; therefore, where they are used inrelatively large quantities, it is important to ensure that heat isconducted through them to produce a relatively even temperaturedistribution and heat transfer profile throughout. This is a key benefitof combining a heat conducting medium with a phase change material in aclosed vessel, and it improves the ability of the system to absorb heatfrom or emit heat to its surrounding environment, particularly overlonger periods.

In an embodiment of the invention, the solid heat conducting medium isdiscrete from the phase change material. This has the advantage ofallowing the heat conducting medium to be separated from the phasechange material, should it be necessary to replace or renew one of thesesubstances only. In contrast, where phase change materials areimpregnated within substrates of substances, when either the phasechange material or the substrate is not performing effectively, thewhole product requires replacement, rather than just one of thefunctional components.

In a further embodiment of the invention, the solid heat conductingmedium is in particulate form. A heat conducting medium in particulateform ensures that it is in contact with the phase change material over arelatively large surface area, with the result that it is able toconduct heat more effectively through the phase change material than itmight otherwise do.

Preferably, the vessel is in the form of a cylindrical tube because sucha configuration is easy to manufacture. Cylindrical tubes are alsoreadily available commercially and allow air to flow freely around theircircumference. However, the vessel could have any alternativeconfiguration, such as a box or a tube with a triangular or squarecross-section.

In another embodiment of the invention, the vessel has fins around itsouter surface. The fins improve heat transfer between the vessel and thesurrounding environment by virtue of the increased surface area thatthey provide on an interface between the vessel and the surroundingenvironment. The fins can be incorporated on the vessel surface by anysuitable means. For example, a sleeve carrying fins could be fittedaround an outer surface of the vessel.

In a yet further embodiment of the invention, the vessel is made ofmetal to further improve heat transfer between the vessel and itssurrounding environment. Aluminum is a particularly preferred metal dueto its favorable malleability, heat conductivity, rigidity and strengthcharacteristics.

It is preferred that the outer surface of the vessel (including any finsarranged thereon) be anodized so that the absorptance and emissivity ofthe outer surface is increased. Similarly, at least a part of the vesselcan be painted to improve absorptance and emissivity.

Preferably, the vessel is configured to be located directly within thespace to be cooled. One benefit of locating the vessel directly in theenvironment it is intended to cool is that it allows the vessel to actpassively to remove heat from the environment. A further benefit oflocating the climate control system directly within the space to becooled, rather than integrating it within the walls, floor or ceilingsurrounding that space is that it mitigates any restriction that theinternal surface area of the space might place on the ability to installthe climate control system. For example, if a climate control system isintended to be incorporated into a wall of the environment to be cooled,the system can only be as big as the relevant wall. By locating theclimate control system directly within the environment to be cooled sothat it does not simply form part of the environment's boundary providesgreater flexibility in the space available for housing the climatecontrol system.

In a further embodiment of the invention, the heat conducting medium isin the form of Lessing rings or Raschig rings. This type of heatconducting medium has been found to be particularly effective due to itsability to penetrate the phase change material and expose a large amountof the phase change material to the heat conducting medium, whichgreatly improves heat transfer and temperature distribution throughoutthe phase change material. Raschig rings, in particular, were found tohave a relatively large void volume. The void volume produced by therings is determined by the diameter, length and gauge of the individualrings and can be varied by varying one or more of these dimensions.Furthermore, both Les sing rings and Raschig rings are easily pourableinto the vessel to form a lattice structure within its internal surface.Where the Raschig or Lessing rings are made of aluminum, which ispreferred, they have favorable heat conducting properties and inaddition, the lattice formed by the rings within the internal surface ofthe vessel is sufficiently rigid to be self-supporting.

As an example alternative heat conducting medium, however,heat-conducting fins on an internal surface of the vessel could serve toconduct heat through the phase change material. Such fins would,preferably, be made of metal, which is a good heat conductor.

In a further embodiment of the invention, the phase change materialchanges state at a peak melt temperature within the range of 18 to 26degrees centigrade. A key advantage to using a phase change material ofthis nature is that it changes state, and would, therefore, be able topassively cool or heat its surrounding environment at a temperature thatis generally considered to be comfortable for humans.

Preferably, the phase change material is a mixture of paraffin andhydrated salt. Paraffin demonstrates non-corrosive characteristics andlong life. Heptadecane is an example of a particularly preferredparaffin because it has an appropriate melt temperature for effectingclimate control for humans and a relatively high energy density. Inaddition, it has a latent heat capacity that is focused around its peakmelt temperature, which makes it very effective at passive heating orcooling. Hydrated salt has the advantage that is has favorable firesafety characteristics. A particularly preferred hydrated salt isNa2CrO4•10H2O.

It is preferred that in a mixture of paraffin and hydrated salt,hydrated salt forms a higher proportion of the mixture by volume thanparaffin, preferably at least 90% of the mixture by volume.

In another embodiment of the invention, at least an internal surface ofthe vessel is coated with a resin for preventing corrosion. In a yetfurther embodiment of the invention, at least an external surface of theheat conducting medium is coated with a resin for preventing corrosion.The benefit of providing corrosion resistance is that it increases theuseful life of the climate control system. A corrosion-resistant resincoating is a practical and inexpensive way of achieving corrosionresistance.

Preferably, the climate control system further comprises an activecooling or heating apparatus. The advantage of incorporating an activecooling or heating apparatus in the system is that there is capacity forsupplementing the passive climate control system in the event thatpassive climate control is not sufficiently effective in certainsituations, for example, on very hot days, or in environments whereequipment is generating an unusually high ambient temperature. Thisprovides a flexible system that can operate over a broad range ofenvironmental conditions. A further benefit of using an active coolingor heating apparatus in the system is that overnight heat emission intothe environment can be guaranteed.

In an embodiment of the invention, a plurality of vessels is included inthe system. This provides the advantage of increasing climate controlcapacity in the environment in which climate is to be controlled.Effectively, the climate control system in accordance with thisembodiment of the invention is modular, permitting as many vessels to beused as are required.

In accordance with a second aspect of the present invention, a method ofcontrolling climate within an environment comprises arranging a closedvessel containing a phase change material and a solid heat conductingmedium in the environment and permitting the vessel to passively controlthe climate within the environment.

Further features and advantages of the invention will become apparentfrom the following description of embodiments of the invention, given byway of example only, which is made with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a climate control system, partially incross-section, in accordance with an embodiment of the invention;

FIG. 2 shows a perspective view of the climate control system of FIG. 1;

FIG. 3 shows a perspective internal end view of the climate controlsystem of FIG. 1;

FIG. 4 shows a cross-sectional view of a solid heat conducting mediumfor a climate control system in accordance with an alternativeembodiment of the invention;

FIG. 5 shows a schematic plan view of a climate control system inaccordance with a further alternative embodiment of the invention in anenvironment in which it is intended to operate; and

FIG. 6 shows a perspective view of a climate control system inaccordance with a yet further alternative embodiment of the invention.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The climate control system described herein comprises a closed vesselcontaining a phase change material for absorbing heat from or emittingheat to an environment in which the system is intended to be arranged;and a solid heat conducting medium for facilitating heat transfer withinthe vessel.

Phase change materials can passively remove heat from or emit heat totheir surrounding environment as they change state due to their highlatent heat capacity. However, phase change materials are not inherentlygood conductors of heat; therefore, heat is not easily distributedthrough phase change materials. In order to improve heat dissipationthrough phase change materials, and to produce a relatively eventemperature distribution throughout, the present climate control systemcombines a heat conducting medium with a phase change material in aclosed vessel.

FIGS. 1 and 2 show a climate control system 1 in the form of acylindrical-shaped, finned tube 2 which contains a phase change material(not shown) and a solid heat conducting medium (described in more detailin connection with FIG. 3 below). A pipe 3 for transporting a heattransfer fluid through the finned tube 2, which forms part of an activecooling and/or heating system, is arranged substantially centrallyinside the finned tube 2 and extends through the full length of the tube2. End caps 4 close the finned tube 2 at both of its ends. The end caps4 can be welded onto the ends of the finned tube 2 or securely attachedto the ends of the finned tube 2 by any other suitable means, includingbolts. It is preferred that the end caps 4 be easily removable from theends of the finned tube 2 but this is not essential. In addition, thejunction between each end of the finned tube 2 and its respective endcap 4 is preferably hermetically sealed, although this is not essential.

The finned tube 2 has a substantially smooth and even inner surface andan outer surface on which a plurality of fins 5 is formed. The fins 5can be formed by machining a wall of a thick-walled hollow cylinder.Alternatively, the finned tube 2 can be formed of a tube with a finnedsleeve mounted on its outer surface. A further way of incorporating fins5 into an outer surface of the tube 2 would be to mount and attach aseries of individual solid rings on the outer surface of the tube.Although it is also possible to include a tube without fins on its outersurface, it will be appreciated that the heat absorption/dissipationcharacteristics of such a tube would be reduced by the effect that theomission of the fins would have on the overall outer surface area of thetube.

The finned tube 2 is preferably made of metal. Forming the finned tube 2of metal enhances its heat conducting ability. Aluminum is particularlypreferred as a material from which to form the finned tube 2 but othermetals are also envisaged, including steel and copper.

The outer metallic surface of the finned tube 2 can also be anodized toincrease the absorptance and emissivity of the surface. Anodisation alsohas the effect of rendering the outer surface more sorbent, which can bebeneficial if the surface is to be dyed. For example, an outer surfaceof the vessel can be dyed black using paint in order to improve itsemittance and absorptance further or it can be dyed white to better suitthe environment in which it is to be located.

The solid heat conducting medium inside the finned tube 1 is preferablyin the form of a random packing 6, such as Raschig rings or Lessingrings. FIG. 3 shows an embodiment of the invention in which the heatconducting medium is in the form of metallic Raschig rings 6. Anadvantage of using a particulate heat conducting medium, such as arandom packing, is that it provides a uniform distribution throughoutthe phase change material so that heat may be conducted to and from allregions of the phase change material relatively equally. Making the heatconducting medium from metal also improves its heat conducting capacityand rigidity. Aluminum is a particularly preferred material for the heatconducting medium but steel and copper would also be viable. Raschigrings of diameter 6 mm and length 6 mm with a 1 mm gauge have found tobe particularly suitable for this purpose.

As an alternative to using a random packing as a heat conducting medium,a number of heat conducting fins 7 could be attached or integrallyformed on an inner surface of the finned tube 2 in a spoke configurationacross the cross-section of the tube 2, as shown in FIG. 4. It isenvisaged that several spokes of heat conducting fins 7 would beprovided along the length of tube 2. The heat conducting fins 7 could bemade of aluminum or any other suitable metallic material, such as copperor steel.

Graphite fibers could be a further alternative heat conducting medium.

In order to avoid corrosion that might result from the phase changematerial that is arranged inside the finned tube 2, an inner surface ofthe tube 2 may be coated with a protective resin. Similarly, thesurfaces of the heat conducting medium can also be coated with the sameprotective resin. A suitable resin for this purpose would be that usedby Rubitherm GmbH.

The phase change material selected for use in the climate control systemis essential to satisfactory functioning of the system. Firstly, a phasechange material must be selected that changes state within a temperaturerange in which climate control is required. Usually, a comfortableambient temperature is considered to be in the range from around 20° C.to around 25° C. Once the temperature drops to around 18° C., it islikely that it will be desirable to heat the environment to bring itback to around 20° C. Similarly, once the ambient temperature rises toabove 25° C., it is likely to be necessary to cool the environment tobring its temperature back down to a comfortable level. It will beappreciated, therefore, that a phase change material that changes statein the range of 18° C. to 26° C. is preferred.

One suitable phase change material is a mixture of paraffin and hydratedsalt; heptadecane is a suitable paraffin because it changes state from asolid to a liquid at 22° C. and has a narrow phase transition zone, sothat its ability to absorb or emit heat during phase change isefficient. Paraffin, generally, is non-corrosive, which is beneficialfor the service life of the finned tube 2 in which it is located.Furthermore, paraffin itself has an extremely high life cycle due to anability to maintain its thermophysical properties over time.

A possible disadvantage of paraffin is that it is highly flammable andthus presents a challenge in terms of managing risk to health andsafety. However, the fact that the paraffin is contained within a closedvessel mitigates this element of risk to a large extent. In addition,the use of a hydrated salt, which is not flammable, can mitigate therisk associated with using paraffin. A hydrated salt, such asNa2CrO4·10H2O would be particularly suitable for this application. Onelimitation of using hydrated salts is that they can be corrosive.However, if the finned tube 2 and the heat conducting medium 6 or 7 iscoated with a protective resin, as outlined above, such corrosion can beavoided.

The mixture of paraffin and hydrated salt includes a higher proportionof hydrated salt than paraffin by volume. The hydrated salt content ofthe mixture can be as high as 95% by volume, for example.

The phase change material inside the finned tube 2 is preferablydiscrete from the heat conducting medium. This has the advantage ofallowing replacement of the phase change material or the heat conductingmedium separately. For example, should a random packing heat conductingmedium 6 degrade over time, it can simply be separated from the phasechange material in the vessel and replaced with a new random packingheat conducting medium 6. Prior art systems that use phase changematerials include a substrate that is impregnated with a phase changematerial; it is not practical to separate the phase change material fromits substrate material so if one element of the composite productdegrades, the whole product needs to be replaced.

Before use, the finned tube 2 is equipped with a heat conducting medium,for example, by attaching heat conducting fins 7 to its internal surface(if they are not already formed on the internal surface of the tube 2)or by filling the tube with the random packing 6 or other suitable solidheat conducting medium. Preferably, an air pocket would be retained atone end of the finned tube 2 in order to allow for expansion of thephase change material and heat conducting medium during phase change.However, expansion and contraction could be accommodated in a differentway, for example, by including a flexible component in the vessel thatcould itself expand and contract in response to expansion andcontraction of the phase change material and heat conducting medium. Oneof the end caps 4 of the finned tube 2 should be removed to provide anopen end of the finned tube 2 to facilitate the filling process.Following insertion of the heat conducting medium 6 or 7, the phasechange medium in liquid form is poured into the finned tube 2 around theheat conducting medium 6 or 7, so that the air pocket remains. It willbe appreciated that it is likely to be necessary to heat the phasechange material to a degree to ensure that it is fully in a liquid statebefore pouring it into the finned tube 2 but it should subsequently cooldown to the ambient temperature and solidify. Once both the heatconducting medium 6 or 7 and the phase change material have beenarranged in the finned tube 2, the end cap 4 that was previously removedcan be attached to the open end of the finned tube 2, either permanentlyby welding or removably by means of mechanical fasteners, such as bolts.The climate control system 1 can then be installed in an environment inwhich it is to be operated. Preferably, the climate control system 1will have attachment means, such as at least one mounting bracket, forfixing it to a surface, for example, to a wall or ceiling, within theenvironment where climate control is required so that the system 1 canbe wholly located within that environment. The pipe 3 that extendsthrough the finned tube 2 must also be connected at each of its ends toa heat transfer fluid transport system in the environment; this couldinclude a pipe network within the environment, a heat transfer fluidreservoir and also a pump (not shown) for pumping the heat transferfluid around the pipe network.

In practice, it is likely that several finned tubes 2 will be includedin the environment in which the climate is to be controlled. The finnedtubes 2 can be arranged in an array 8, as shown in FIG. 5, for example,and can be several layers deep in each of two dimensions. An importantadvantage of being able to arrange a plurality of finned tubes 2 in thismanner is that it permits a very flexible, effectively modular climatecontrol system to be provided. The number of finned tubes 2 can beselected according to climate control requirements and the number is notsignificantly constrained by the surface area of walls or ceilings inthe environment to be cooled.

Since the finned tube 2 or the array 8 of finned tubes is intended to belocated directly in the environment in which the climate is to becontrolled, it is important that they are aesthetically pleasing. It ispossible, for example, that the finned tubes 2 could be coated incolored dye or paint (other than black dye, as suggested above).Similarly, the shape of the finned tubes 2 could be other thancylindrical. An alternative configuration of finned tube in the form ofa tube with a triangular cross-section is shown in FIG. 6, for example.A finned tube with a square cross-section is also envisaged.

In use, as the temperature in the environment rises, the phase changematerial inside the finned tube 2 starts to warm up. When the phasechange material reaches its melting point it changes phase from a solidto a liquid, thereby absorbing heat from the environment in which theclimate control system is located and reducing the ambient temperatureof that environment. Various features of the system enhance heattransfer from the environment and through the finned tube 2. Inparticular, the fins 5 increase the surface area of the tube that isexposed to the environment, thus improving heat transfer between theenvironment and the finned tube 2. Within the finned tube 2, the heatconducting medium 6 or 7 ensures that heat is conducted through thephase change material in the finned tube 2 to be evenly distributedthroughout. Without the heat conducting medium, it is likely that onlypart of the phase change material would be sufficiently exposed to heatfrom the surrounding environment to change state from a solid to aliquid. It is important that as much of the phase change materialchanges state as possible so that the climate control system 1 operateseffectively by absorbing a maximum amount of heat from the surroundingenvironment.

In the event that the change of state of the phase change material froma solid to a liquid is insufficient to absorb all of the excess heatfrom the surrounding environment, a sensor, such as a thermostatarranged within the environment (not shown) will detect that this is thecase and send a signal to initiate operation of an active coolingapparatus (not shown) within the climate control system. In addition oras an alternative, a thermometer or a series of thermometers within thevessel could detect whether all of the phase change material in thevessel had changed state and respond by initiating operation of theactive cooling apparatus in the event that it had. The active coolingapparatus may use a pump (not shown) to pump a heat transfer fluid froma heat sink such as a chiller or a night sky cooling panel through thepipe 3 of the climate control system. The heat transfer fluid ispreferably chilled water because this is an inexpensive, easy substancewith which to work but it could equally be an alternative heat transferfluid, such as a slurry containing a phase change material.

Pumping a heat transfer fluid through the pipe 3 serves to cool thephase change material so that it can absorb further heat from thesurrounding environment.

Once the ambient temperature drops and it is perceptible that activecooling is no longer required, the active cooling apparatus can bede-activated. When the temperature drops further (or there is an initialdrop in the case where active cooling was not employed at all), forexample, because it is night-time or because certain heat generatingequipment is no longer being used in the environment, the phase changematerial starts to re-solidify and emit heat into the environment.

Although the discussion above focuses primarily on operating the climatecontrol system as a cooling system 1, it could also be used as a heatingsystem by operating in reverse. As the temperature in the surroundingenvironment cools, the phase change material would start to freeze,releasing heat into the surrounding environment. Once the phase changematerial was completely frozen, if it was detected that the surroundingenvironment needed to be heated further, an active heating apparatuscould pump a hot fluid, such as hot water, from a storage reservoir,where the fluid could be heated, through the pipe 3 of the climatecontrol system. The passage of the hot fluid through the pipe 3 wouldserve to heat the phase change material, providing further capacity forit to emit heat to the surrounding environment.

Once the environment was sufficiently warm, if an active heatingapparatus had been deployed, that could be switched off. Alternatively,if there was no active heating or in addition, if active heating hadbeen switched off and the environment warmed up to an acceptabletemperature, the phase change material would melt again, thus absorbingheat from the environment.

It will be appreciated that the climate control system essentiallycycles through freezing and melting of the phase change material inresponse to temperature changes in the surrounding environment, therebypassively controlling the environment temperature as far as possible. Tothe extent that further heating or cooling is required, an activeheating and/or cooling apparatus can be used supplementally.

The above embodiments are to be understood as illustrative examples ofthe invention. Further embodiments of the invention are envisaged. Forexample, it is possible that an active cooling and/or heating apparatuswould be omitted from the climate control system 1 so that the systemwould operate entirely passively. Active heating and cooling assembliescould be combined in a single unit that would selectively heat or chillthe heat transfer fluid. There may be a storage reservoir for storingthe heat transfer fluid and for heating it or cooling it before it ispassed through the pipe network.

It would be possible to integrate the climate control system describedherein with a ventilation system for the environment. This would permitheat to be discharged to circulate cool night air within theenvironment, for example.

It is envisaged that the system could be programmed to automaticallyactively discharge heat at a certain time of night when the temperaturein the environment was expected to be sufficiently low to be capable ofabsorbing the discharged heat.

It is not essential for the tube 2 to have fins 5 on its outer surface.Instead it could have a substantially smooth profile.

The finned tube 2 does not have to be made from metal; any othersuitable non-metallic material with satisfactory thermal characteristicscould be used as an alternative. It will be appreciated, however, thatnon-metallic materials that are good thermal insulators will not beappropriate for the finned tube 2, as such materials would prevent heattransfer from the surrounding environment to the phase change material.

The pipe 3 does not have to be arranged substantially centrally withinthe finned tube 2 and could be eccentrically arranged therein.Furthermore, more than one pipe could be arranged within the finned tube2.

Rather than being wholly located in the environment in which climate isbeing controlled, the climate control system 1 could be only partiallyexposed to the environment. For example, the system 1 could be mountedin the ceiling, floor or wall of a space in which the climate is to becontrolled so that only a portion of its external surface is in thespace. The system 1 could be contained within a separate closable unitin the environment in which the climate is being controlled, so that thesystem could effectively be shut off from the environment, for example,by closing shutters or doors on the unit, when required.

Rather than using a combination of hydrated salt and paraffin, the phasechange material could comprise only hydrated salt or only paraffin, orany other suitable phase change material. It will be appreciated that incertain circumstances the selected phase change material may comprise ashape-stabilized material, which would mean that it may not need to beenclosed within a vessel, although health and safety constraintsregarding direct exposure of the environment to the phase changematerial will also need to be taken into account. Furthermore,encapsulating the phase change material within a vessel has theadvantage of permitting easier handling and cleaning of the system andalso providing increased strength and rigidity.

It is to be understood that any feature described in relation to any oneembodiment may be used alone, or in combination with other featuresdescribed, and may also be used in combination with one or more featuresof any other of the embodiments, or any combination of any other of theembodiments. Furthermore, equivalents and modifications not describedabove may also be employed without departing from the scope of theinvention, which is defined in the accompanying claims.

What is claimed is:
 1. A climate control system comprising: a closedvessel, the closed vessel including: a phase change material forabsorbing heat from or emitting heat to an environment in which thesystem is intended to be arranged; and a solid heat conducting mediumfor facilitating heat transfer within the vessel, wherein the solid heatconducting medium is in the form of a random packing.
 2. The climatecontrol system of claim 1, wherein the solid heat conducting medium isdiscrete from the phase change material.
 3. The climate control systemof claim 1, wherein the solid heat conducting medium is in particulateform.
 4. The climate control system of claim 1, wherein the vessel is inthe form of a cylindrical tube.
 5. The climate control system of claim1, wherein the vessel is in the form of a tube with a triangular orsquare cross-section.
 6. The climate control system of claim 1, whereinthe vessel has fins around its outer surface.
 7. The climate controlsystem of claim 6, wherein the fins are arranged on a sleeve that isconfigured to fit around the outer surface of the vessel.
 8. The climatecontrol system of claim 1, wherein the vessel is made of metal.
 9. Theclimate control system of claim 1, wherein the vessel is made ofaluminum.
 10. The climate control system of claim 8, wherein at least anouter surface of the vessel is anodized.
 11. The climate control systemof claim 9, wherein at least an outer surface of the vessel is anodized.12. The climate control system of claim 1, wherein at least a part ofthe vessel is colored.
 13. The climate control system of claim 1,wherein the vessel is configured to be located directly within the spaceto be cooled.
 14. The climate control system of claim 1, wherein therandom packing comprises Lessing rings.
 15. The climate control systemof claim 1, wherein the random packing comprises Raschig rings.
 16. Theclimate control system of claim 1, wherein the heat conducting medium ismade of metal.
 17. The climate control system of claim 1, wherein acharacteristic of the phase change material is that it changes state ata peak melt temperature within the range of 18° C. to 26° C.
 18. Theclimate control system of claim 1, wherein the phase change material isa mixture of paraffin and hydrated salt.
 19. The climate control systemof claim 18, wherein the paraffin is heptadecane.
 20. The climatecontrol system of claim 18, wherein the hydrated salt isNa₂CrO₄•10H₂O.11
 21. The climate control system of claim 1, wherein thephase change material is a hydrated salt.
 22. The climate control systemof claim 1, wherein the phase change material is paraffin.
 23. Theclimate control system of claim 1, wherein at least an internal surfaceof the vessel is coated with a resin for preventing corrosion.
 24. Theclimate control system of claim 1, wherein at least an external surfaceof the heat conducting medium is coated with a resin for preventingcorrosion.
 25. The climate control system of claim 1, further comprisingan active cooling and/or heating apparatus.
 26. The climate controlsystem of claim 25, wherein the active cooling and/or heating apparatuscomprises a pipe that is configured to carry a heat transfer fluidthrough the vessel.
 27. The climate control system of claim 26, whereinthe heat transfer fluid is water.
 28. The climate control system ofclaim 26, wherein the active cooling and/or heating apparatusadditionally includes a pump to pump the heat transfer fluid through thepipe.
 29. The climate control system of claim 27, wherein the activecooling and/or heating apparatus additionally includes a pump to pumpthe heat transfer fluid through the pipe.
 30. The climate control systemof claim 1, wherein a plurality of vessels is included in the system.31. A building comprising a climate control system, wherein the climatecontrol system comprises: a closed vessel, wherein the closed vesselcomprises: a phase change material for absorbing heat from or emittingheat to an environment in which the system is intended to be arranged;and a solid heat conducting medium for facilitating heat transfer withinthe vessel, wherein the solid heat conducting medium is in the form of arandom packing.
 32. The building of claim 31, wherein the climatecontrol system is located directly within a space in which climate is tobe controlled.
 33. The building of claim 32, wherein the climate controlsystem is located partially in a wall, floor or ceiling of the building.34. A method of controlling climate within an environment comprising:arranging a closed vessel comprising a phase change material and a solidheat conducting medium in the environment; and permitting the vessel topassively control the climate within the environment, wherein the solidheat conducting medium is in the form of a random packing.